/*
Copyright 2020 The KubeSphere Authors.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package authorizer

import (
	"net/http"

	"k8s.io/apiserver/pkg/authentication/user"
)

// NOTE: This file is copied from k8s.io/kubernetes/apiserver/pkg/authorization/authorizer.
// We have expanded some attributes, such as workspace and cluster.

// Attributes is an interface used by an Authorizer to get information about a request
// that is used to make an authorization decision.
type Attributes interface {
	// GetUser returns the user.Info object to authorize
	GetUser() user.Info

	// GetVerb returns the kube verb associated with API requests (this includes get, list, watch, create, update, patch, delete, deletecollection, and proxy),
	// or the lowercased HTTP verb associated with non-API requests (this includes get, put, post, patch, and delete)
	GetVerb() string

	// When IsReadOnly() == true, the request has no side effects, other than
	// caching, logging, and other incidentals.
	IsReadOnly() bool

	// Indicates whether or not the request should be handled by kubernetes or kubesphere
	IsKubernetesRequest() bool

	// The cluster of the object, if a request is for a REST object.
	GetCluster() string

	// The workspace of the object, if a request is for a REST object.
	GetWorkspace() string

	// The namespace of the object, if a request is for a REST object.
	GetNamespace() string

	// The devops project of the object, if a request is for a REST object.
	GetDevOps() string

	// The kind of object, if a request is for a REST object.
	GetResource() string

	// GetSubresource returns the subresource being requested, if present
	GetSubresource() string

	// GetName returns the name of the object as parsed off the request.  This will not be present for all request types, but
	// will be present for: get, update, delete
	GetName() string

	// The group of the resource, if a request is for a REST object.
	GetAPIGroup() string

	// GetAPIVersion returns the version of the group requested, if a request is for a REST object.
	GetAPIVersion() string

	// IsResourceRequest returns true for requests to API resources, like /api/v1/nodes,
	// and false for non-resource endpoints like /api, /healthz
	IsResourceRequest() bool

	// GetResourceScope returns the scope of the resource requested, if a request is for a REST object.
	GetResourceScope() string

	// GetPath returns the path of the request
	GetPath() string
}

// Authorizer makes an authorization decision based on information gained by making
// zero or more calls to methods of the Attributes interface.  It returns nil when an action is
// authorized, otherwise it returns an error.
type Authorizer interface {
	Authorize(a Attributes) (authorized Decision, reason string, err error)
}

type AuthorizerFunc func(a Attributes) (Decision, string, error)

func (f AuthorizerFunc) Authorize(a Attributes) (Decision, string, error) {
	return f(a)
}

// RuleResolver provides a mechanism for resolving the list of rules that apply to a given user within a namespace.
type RuleResolver interface {
	// RulesFor get the list of cluster wide rules, the list of rules in the specific namespace, incomplete status and errors.
	RulesFor(user user.Info, namespace string) ([]ResourceRuleInfo, []NonResourceRuleInfo, bool, error)
}

// RequestAttributesGetter provides a function that extracts Attributes from an http.Request
type RequestAttributesGetter interface {
	GetRequestAttributes(user.Info, *http.Request) Attributes
}

// AttributesRecord implements Attributes interface.
type AttributesRecord struct {
	User              user.Info
	Verb              string
	Cluster           string
	Workspace         string
	Namespace         string
	DevOps            string
	APIGroup          string
	APIVersion        string
	Resource          string
	Subresource       string
	Name              string
	KubernetesRequest bool
	ResourceRequest   bool
	Path              string
	ResourceScope     string
}

func (a AttributesRecord) GetUser() user.Info {
	return a.User
}

func (a AttributesRecord) GetVerb() string {
	return a.Verb
}

func (a AttributesRecord) IsReadOnly() bool {
	return a.Verb == VerbGet || a.Verb == VerbList || a.Verb == VerbWatch
}

func (a AttributesRecord) GetCluster() string {
	return a.Cluster
}

func (a AttributesRecord) GetWorkspace() string {
	return a.Workspace
}

func (a AttributesRecord) GetNamespace() string {
	return a.Namespace
}

func (a AttributesRecord) GetDevOps() string {
	return a.DevOps
}

func (a AttributesRecord) GetResource() string {
	return a.Resource
}

func (a AttributesRecord) GetSubresource() string {
	return a.Subresource
}

func (a AttributesRecord) GetName() string {
	return a.Name
}

func (a AttributesRecord) GetAPIGroup() string {
	return a.APIGroup
}

func (a AttributesRecord) GetAPIVersion() string {
	return a.APIVersion
}

func (a AttributesRecord) IsResourceRequest() bool {
	return a.ResourceRequest
}

func (a AttributesRecord) IsKubernetesRequest() bool {
	return a.KubernetesRequest
}

func (a AttributesRecord) GetPath() string {
	return a.Path
}

func (a AttributesRecord) GetResourceScope() string {
	return a.ResourceScope
}

type Decision int

const (
	// DecisionDeny means that an authorizer decided to deny the action.
	DecisionDeny Decision = iota
	// DecisionAllow means that an authorizer decided to allow the action.
	DecisionAllow
	// DecisionNoOpionion means that an authorizer has no opinion on whether
	// to allow or deny an action.
	DecisionNoOpinion
)

const (
	// VerbList represents the verb of listing resources
	VerbList = "list"
	// VerbCreate represents the verb of creating a resource
	VerbCreate = "create"
	// VerbGet represents the verb of getting a resource or resources
	VerbGet = "get"
	// VerbWatch represents the verb of watching a resource
	VerbWatch = "watch"
	// VerbDelete represents the verb of deleting a resource
	VerbDelete = "delete"
)
